Issue of options under equity incentive plan - Fair value inputs (Detail) (2010 Equity Incentive Plan, USD $)	6 Months Ended
	Apr. 30, 2013	May 01, 2011
Options Vested on December 13, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date	Dec. 13, 2010
Grant date share price	$ 1.1
Expected life in years	4 years 6 months
Risk-free rate	1.91%
Volatility	95.00%
Exercise price	$ 1
Call option value	$ 0.78
Options Vested on November 17, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date	Dec. 13, 2010
Grant date share price	$ 1.1
Expected life in years	5 years
Risk-free rate	1.91%
Volatility	95.00%
Exercise price	$ 1
Call option value	$ 0.81
Options Vesting on November 17, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date	Dec. 13, 2010
Grant date share price	$ 1.1
Expected life in years	5 years 6 months
Risk-free rate	1.91%
Volatility	95.00%
Exercise price	$ 1
Call option value	$ 0.83
Options Vested on May 1, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date	May 01, 2011
Grant date share price		$ 1.3
Expected life in years	3 years 6 months
Risk-free rate	2.02%
Volatility	100.00%
Exercise price	$ 1
Call option value	$ 0.91
Options Vested on February 1, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date	May 01, 2011
Grant date share price		$ 1.3
Expected life in years	4 years
Risk-free rate	2.02%
Volatility	100.00%
Exercise price	$ 1
Call option value	$ 0.95
Options Vesting on February 1, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date	May 01, 2011
Grant date share price		$ 1.3
Expected life in years	4 years 6 months
Risk-free rate	2.02%
Volatility	100.00%
Exercise price	$ 1
Call option value	$ 0.99